My 1969 F100 Big Block Six 240 Holley Sniper EFI Train Wreck Project

[PSIG]

Data. It hold clues to the solutions. Keeping in-mind the Lambda sensor is 50 to 200 milliseconds behind in reading, and that data is serial so it does not always show the logical order of engine response (chicken or egg); relationships between TPS, AFR, RPM and other data can be the top tuning troubleshooter. That's why it's called diagnostic tuning.

1) does not like to "lug" if you are at ~1000 to ~1500 RPM and put your foot down it will stumble.

The data should show the stumble area (MAPxRPM) and if it goes lean or rich. If it goes lean, it could be ignition under load, or lean accel fuel. The easy check is to manually add substantial fuel in the lean area (10-20%) in the table, and check data for response. If no change, it's likely ignition. If rich, just pull fuel.

2) Russian roulette starting. Most times starts right up. Some times it fires and then dies.

This can sometimes be a simple oddity, such as how fast it is keyed from OFF through RUN to START, too quick for pressure to build for cranking and it leans and stalls. This indicates an internal fuel pressure leak and not enough time to pump it back up. Usually the regulator, but sometimes a leaky injector. Another thing I've seen is a jittery ignition switch, causing a 'skip' in power and a reset, causing a double prime and balky start. Again, data holds useful clues when you play 'Where's Waldo'.

 

[PSIG]

Every time Engine Masters tests a TBI system against a carb, the carb wins every time. The carb has better max power, and they think the reason is because the TBI has much worse cylinder-to-cylinder distribution. The mixture variation between cylinders is terrible with TBI- worse than a carb's distribution without exception or engine configuration.

Fuel distribution with an inline six is poor with any central fueling, and one of the primary handicaps of the configuration. Carbs struggle with this also, and why Ford went to MPFI without the in-between CFI (TBI) used on 4s and V8s. The issue isn't all TBI, but those that have fewer injections per-cycle than cylinders, which magnifies the issue. In Europe, with high inline 6 popularity and high fuel prices, constant-flow central injection was used to avoid this uneven fueling.

Distribution has been shown to be carb-equivalent when the system fires an injection for every cylinder (six per cycle). Most commercial box kits don't do this. Some DIY and high-end systems can. In applications that require better fuel distribution (e.g., high-HP, economy competition or power adders), I would suggest MPFI in order to jump past all those issues, else 6-squirt TBI for carb-equivalent distribution with better control.

 

[Frank]

Telling the ECM to add fuel in the trouble area may not be a fix. 63Sprint had an extended terrible experience with Holly TBI 2V on a Offy C intake: while the unsuspended fuel accumulated in the runners when cold/low rpm- (particularly the rear runners, as the aftermarket intakes are not tilted downward to compensate for the engine's plane), the ECM correctly read lean and added more fuel. Once enough throttle was applied to move the raw fuel the over-richness was severe enough to cause complete misfire, stumbling and poor economy.

 

[DON]

I’m not sure if he mentioned it to be a fix, but rather an indicator of it making it better or worse, a diagnostic method if you will. But not sure of that

 

[PSIG]

+1 to Don's assessment - it was a diagnostic indicator, not a fix. For 63 Sprint's issue, yes that's wall-wetting, and a problem for any central fueling. Ford's EEC-III CFI (TBI) used table enrichment that I described to cover areas that would not provide accel fuel well, too late into the accel (runner velocity had already fallen too low resulting in fuel dropout, wetting/puddling). Fortunately, the only time the low-rpm and high-MAP go there is in accel, so enriching the table is harmless for other driving.

One potential solution is progressive carb bores, and another is dual-plane, in order to increase carb and runner velocity and vaporization at lower speeds and loads, especially when cold which magnifies the issue. I had this exact issue on a 3/4 ton TBI V8, even when hot, as it would puddle on decel (low airflow) and go rich when it settled to idle or added throttle where the fuel vaporized and went hard rich. Closing the plenum for full dual-plane helped a lot, maintaining better fuel suspension. Opening the idle air bypass for 'cleaning' flow and cutting fuel during puddling recovery conditions did the rest. Unfortunately, an option not possible with carbs.

 

[Bronctopia]

One potential solution is progressive carb bores,

Always did like the Quadrajet for that reason.
Tiny start/idle/cruise primaries, and huge secondaries for that 5% of driving where you actually need a big block to make noise and thrust in wholesale quantities.

 

[63 Sprint]

Telling the ECM to add fuel in the trouble area may not be a fix. 63Sprint had an extended terrible experience with Holly TBI 2V on a Offy C intake: while the unsuspended fuel accumulated in the runners when cold/low rpm- (particularly the rear runners, as the aftermarket intakes are not tilted downward to compensate for the engine's plane), the ECM correctly read lean and added more fuel. Once enough throttle was applied to move the raw fuel the over-richness was severe enough to cause complete misfire, stumbling and poor economy.

Very bad memories, Wow! Frank you had to bring it up.

When you have to spend days on the phone waiting and talking to Holley tech support, there is a problem.

The Sniper 2300 was the biggest piece of junk ever made. In less than one year, the first one went bad. Holley sent me another after hours of trouble shooting with them over the phone. Installed the replacement and same thing. They sent me a new SIM card with an update. Worked, but not very well. Then the touchscreen went. Sent me another. Then the truck was stalling, bucking and running very poorly. Took it off and sent it in for repairs. It took over six weeks for Holley to just look at it. When they got to it. They said it was fixed. Got it back and it was never touched. They did nothing. I went ballistic! The reason I know it was not touched is I took pictures before I sent it in for repairs.

Called Holley and got the tech support manager. We went over it for about a half hour.He agreed that it was never touched and was apologetic. He sent me the third 2300 and I sold it to recoup some of the loss and used the money to buy the Holley 390. That was the wisest decision. And to this day, every time someone brings up Holley Sniper I get sick.

I did not waste hours. I wasted days, weeks working on those pieces of junk. Over 2 years of headaches. And all I got from Holley is promises.

Holley gets a grade of (F-) for the Sniper products and customer support.

I lost about $1,500.00 to date on that fiasco. And, now the engine will need a rebuild because of cylinder washing and detonation.

If anyone has a daily driver and depends on their truck every day, I Would Not Recommend Anyone To Use A Holley Sniper. Do yourselves a favor. Get a carb and learn how to set it up and tune it. And invest in an AFR meter and a vacuum gauge.

 

[Bronctopia]

And to this day, every time someone brings up Holley Sniper I get sick.

I had the mirror image experience back in the early 2Ks with the then new Holley Truck Avenger carb.
Spent a lot of money for a new product that just refused to perform as advertised.
Later it turned out they had screwed the casting on the first batches.
By then I had thrown in with fuel injection.
Eventually soldering up Megasquirten.
I think the Holley run-around machine made me feel about carbs what they made you feel about EFI.